ruby/rubygems · error · Gem::Security::Exception

certificate #{signer.subject} does not match the signing key

Error message

certificate #{signer.subject} does not match the signing key

What it means

Error "certificate #{signer.subject} does not match the signing key" thrown in ruby/rubygems.

Source

Thrown at lib/rubygems/security/policy.rb:119

    if issuer && !signer.verify(issuer.public_key)
      raise Gem::Security::Exception,
            "#{message} was not issued by #{issuer.subject}"
    end

    true
  end

  ##
  # Ensures the public key of +key+ matches the public key in +signer+

  def check_key(signer, key)
    unless signer && key
      return true unless @only_signed

      raise Gem::Security::Exception, "missing key or signature"
    end

    raise Gem::Security::Exception,
      "certificate #{signer.subject} does not match the signing key" unless
        signer.check_private_key(key)

    true
  end

  ##
  # Ensures the root certificate in +chain+ is self-signed and valid for
  # +time+.

  def check_root(chain, time)
    raise Gem::Security::Exception, "missing signing chain" unless chain

    root = chain.first

    raise Gem::Security::Exception, "missing root certificate" unless root

    raise Gem::Security::Exception,

View on GitHub (pinned to 86cbb817a3)

Solutions

1. Use the certificate that matches the gem's signing key (correct cert/key pair)

When it happens

Trigger: Thrown at lib/rubygems/security/policy.rb:119 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• SSL/TLS and certificate errors — how TLS handshakes and certificate validation fail.

AI-assisted analysis of ruby/rubygems@86cbb817a3 (2026-08-23). Data as JSON: /api/errors/e2e66ccf073a2d9a. Report an issue: GitHub.